Technical Field
Embodiments of the present disclosure generally relate to the field of touch display technology, and particularly, to an optical fingerprint/palmprint identification device, and, a touch display panel and a display apparatus including the identification device.
Description of the Related Art
Fingerprint or palmprint is innately and uniquely identification features of a human body distinguishing from others. Print line features, such as ridge lines and valley lines, are its most important ones, and include a series of ridges and valleys on a skin surface of a finger or palm. Fingerprint or palmprint identification technology owns advantages such as high accuracy, fast speed, low cost, great user acceptance and the like, and is applied progressively onto field of personal identity verification.
Optical fingerprint or palmprint identification technology is mainly based on principle of refraction and reflection of light. When a surface of a touch screen of a display apparatus is pressed by a finger or palm, rugged print lines of the finger or the palm is irradiated by a built-in light source of the display apparatus. Because of different angles at which light is refracted at convex points and concave points of the lines and different intensities of the reflected light, the light projected onto a photosensitive sensor will generate different currents. By detecting the currents, positions of the ridges and valleys of the fingerprint or palmprint are identified. Ridge lines and valley lines are displayed using different colors, so that a fingerprint or palmprint image can be achieved.
In theory, it is able to distinguish absolute positions of the ridges and valleys of the fingerprint or palmprint, as long as the photosensitive sensor is sensitive enough. However, in practical operations, it is difficult to distinguish the ridges and valleys from each other as values of the currents generated by the ridges and valleys are smaller.